Grinding machine with loader and work supporting shoes

ABSTRACT

In a grinding machine of the type in which a workpiece is rotatably supported on a pair of shoes, one of the shoes is fixedly mounted adjacent a grinding wheel, while the other is movably mounted opposite the grinding wheel and downwardly discharges a completed workpiece from a working station when it is moved away from the grinding wheel. In co-operation with the retracting movement of the movable shoe, a loading arm transfers a yet unoperated-on workpiece from a ready station to the working station where a diameter of the workpiece is measured by a movable feeler mounted on a sizing device contacting the workpiece at a position thereon opposite the two points of contact of the shoes.

[ July 17,1973

[ GRINDING MACHINE WITH LOADER AND WORK SUPPORTING SHOES [75] Inventor: Makoto Kikuchi, Kariya-shi, Japan [73] Assignee: Toyoda Koki Kabushiki Kaika,

Aichi-ken, Japan 22 Filed: May 28,1971

21 Appl.No.: 147,815

[30] Foreign Application Priority Data 51/103 C, 215 R, 215 AR, 215 HM, 215 CP, 215 H, 165.91

[56] References Cited UNITED STATES PATENTS 2,635,395 4/1953 Arms 51/215 R UX 2,912,798 11/1959 Seidcl ..5l/103 WH l/1961 Mehlhope 5l/l65.9l X

2,793,479 5/1957 Arms 5l/165.9l X 3,158,965 12/1964 Lockwood 5l/165.91 X

Primary ExaminerDonald G. Kelly Attorney-Oblon, Fisher & Spivak [57] ABSTRACT In a grinding machine of the type in which a workpiece is rotatably supported on a pair of shoes, one of the shoes is fixedly mounted adjacent a grinding wheel, while the other is movably mounted opposite the grinding wheel and downwardly discharges a completed workpiece from a working station when it is moved away from the grinding wheel. ln co-operation with the retracting movement of the movable shoe, a loading arm transfers a yet unoperated-on workpiece from a ready station to the working station where a diameter of the workpiece is measured by a movable feeler mounted on a sizing device contacting the workpiece at a position thereon opposite the two points of contact of the shoes.

16 Claims, 16 Drawing Figures PATENIE JUL 1 7 ms sum 01 or IN VENTOR MAKOTO KlKUCHl ATTORNEY PATENTEUJUH H918 3. 745.723

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PATENIEDJULI 7191a sum 110F PAIENIEU JUL 1 71975 SHEET 1 2 BF PATENIEB JUL 1 1 4913 SHEET -13 0F Qwwx K\ 116 MQ\ 3 m m av GRINDING MACHINE WITH LOADER AND WORK SUPPORTING SHOES BACKGROUND OF THE INVENTION The present invention relates generally to machine tools and more particularly pertains to a centerless grinding machine of the type where a workpiece is rotatably supported on a pair of shoes.

In special purpose machine tools, such as grinding machines for quantity production of bearing races, it is important that the rate of production of the machines be as high as possible. Therefore, it is desirable not only to increase the grinding speed, but also to reduce to a minimum the unproductive periods of loading, unloading, and making sizing operations, during which the workpiece is not being ground.

In conventional work handling machanisms of machines of this type, an unground workpiece is transferred from a loading station to a working station while a completed workpiece, or one which has been operated on by the machine, is being transferred from the working station to a delivery station. Thus, the work handling mechanism must be provided with loading and unloading arms to transfer the workpieces so as to prevent the workpieces being loaded and unloaded from striking on the fixedly mounted shoe. Since a work-loading locus of the loading arm, however, intersects with a work-unloading locus of the unloading arm, the two arems are justly provided with a relatively long swinging stroke and a motion associated therebetween so as not to interfere with each other, thereby increasing the period of unproductivity in comparision with the grinding period. Besides, a spare stroke of escapement-feed movement is generally rendered to a wheel head for preventing the workpiece from striking on the grinding wheel when the workpiece is transferring into the working station or into the delivery station.

In a sizing operation, it is difficult for a sizing device to measure a work diameter not only accurately, but also quickly, without interfering with the loading and unloading arms and the transferring workpiece, since the pair of shoes is generally fixedly mounted and the workpiece is transferred by the two transfer arms or a considerably complicated single transfer arm of the work handling mechanism.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an improved grinding machine of the type characterized by a workpiece being supported on shoes, with high efficiency owing to a reduction in the amount of unproductive time.

It is another object of the present invention to provide an improved grinding machine in which a workpiece may be transferred into and out of a working station without striking the grinding wheel, and in which a spare stroke of feed movement of a wheel'head' is not required,thereby effectively reducing the unproductive time of the machine to a minimum.

It is another object of the present invention. to provide an efficient grinding machine with a work handling mechanism in which a rear shoe is almost laterally shiftedto a retracted position so that a workpiece to be ground maybe swung and transferred by a loading arm into a working station without striking the grinding wheel.

It is still another object of the present invention to provide a grinding machine with a loader mechanism in which a workpiece to be operated on may be transferred into a working station from a ready station adjacent a slightly slanting upper part, and simultaneously a completed workpiece may be downwardly discharged, whereby interference therebetween is prevented and the spare stroke of the transfer arms is made shorter.

It is further an object of the present invention to provide a grinding machine with an improved sizing device having high sensitivity in which a measuring feeler is held in contact with the upper peripheral surface of a workpiece on the opposite side of two lower points of contact of a pair of shoes whereby a greater displacement amount of workpiece relative to the changing amount of its diameter may be measured.

A still further object of the present invention is to provide a grinding machine with an improved sizing device suitable for external centerless grinding operations of the type where a workpiece is supported on shoes and in which the workpieces are loaded and unloaded in a shorter locus without striking the shoes owing to the retracting movement of one of the shoes.

Briefly, according to the present invention, these and other objects are achieved by providing a grinding machine which comprises a bed, a wheel head slidably mounted on the bed for rotatably supporting a grinding wheel, a feed device for moving the wheel head toward and away from a workpiece, a pair of shoes for rotatably supporting the workpiece at a working station adjacent the grinding wheel, driving means for rotating the workpiece, transfer means mounted on the bed for transferring the workpiece into and out of the working station, and a sizing device for measuring the diameter of the workpiece supported at the working station. Furthermore, the front shoe of the pair of shoes is fixedly mounted on the bed adjacent to the grinding wheel in supporting engagement with the lower front portion of the workpiece, while the rear shoe is movably mounted opposite the grinding wheel for downwardly discharging an operated workpiece from the working station when it is moved away from the grinding wheel. The transfer means comprises a loading arm rotatably mounted for transferring a workpiece to be ground from a ready station adjacent a loading chute to the working station in association. with the movement of the rear shoe, and an unloading arm rotatably mounted for facilitating the discharge of a workpiece on which the grinding operation is complete from the working station to a discharge chute. The arms shift in unison toward the unoperated workpieces at their ready sta- DESCRIPTION OF THE DRAWINGS The foregoing and other objects of the present invention will be more fully appreciated as the same becomes better understood from the following description of a preferred embodiment when considered in connection with the accompanying drawings, in which:

FIG. 1 is a front view showing a grinding machine equipped with a loading apparatus constructed according to the present invention;

FIG. 2 is an enlarged view showing a loader mechanism positioned adjacent to a working station;

FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a sectional view taken along the line IV-IV of FIG. 3;

FIG. 5 is a sectional view taken along the line V-V of FIG. 4;

FIG. 6 is a sectional view taken along the line VI-Vl of FIG. 5;

FIG. 7 is a partly sectioned rear view of the loading mechanism of the invention;

FIG. 8 is a schematic diagram of a hydraulic control circuit for the driving mechanism of this invention;

FIG. 9 is a fragmentary schematic view of a cam transmission mechanism for swinging a shoe-rotating arm and an unloading arm;

FIG. 10 is a schematic view showing the operational relationship and positions of an unloading arm and a rear shoe;

FIG. 11 is a schematic view of the cam transmission mechanism for swinging the loading arm;

FIG. 12 is a schematical view showing the operational relationship and position of the loading arm;

FIG. 13 is a fragmentary schematic view showing the cylindrical cam transmission mechanism for axially driving the loading and unloading arm-shafts and showing the operational relationship of the arm-shafts;

FIG. 14 is a schematic view showing a moment caused by an eccentric location of a workpiece;

FIG. 15 is an enlarged front view showing a sizing device; and

FIG. 16 is a fragmentary sectional view showing the left side of the sizing device.

DESCRIPTION OF A PREFERRED EMBODIMENT In FIG. 1, the reference numeral 1 designates a bed on which a wheel head 2 is slidably mounted to be moved in a longitudinal direction thereon by a conventional feed device 3 which may comprise a fluid actuator, feed screw driven by the fluid actuator, and the like. A grinding wheel compensating device 4 is mounted on the wheel head 2 to move the wheel head 2 a compensating feed amount in accordance with a decrease in the grinding wheel diameter, which is caused by a grinding wheel truing device 5. The truing device 5 is slidably mounted on a base 5c and is transversely moved relative to the wheel head direction of movement by a fluid actuator, not shown, so that a diamond truing cutter 5a thereof may traverse the surface of a grinding wheel in a direction parallel to the wheel axis to dress the grinding wheel S. The truing cutter 5a is rotatably carried by the grinding wheel truing device 5 and is rotated by a drive motor 5b mounted on the rear of truing device 5. The grinding wheel S is rotated by a grinding wheel drive motor 6, the shaft of which is held in driving connection with a grinding wheel shaft 7 through belts and pulleys in a well-known manner.

On the left portion of bed 1, as viewed in FIG. 1, a base 11 is mounted to fixedly carry a body 12 of a loading fixture opposite the wheel head 2, a headstock 13, and a work support 14, on which a sizing device 160 is adjustably mounted to measure the diameter of a workpiece.

The detailed construction of each part will be described hereunder with reference to FIG. 2 and below.

The head stock 13 rotatably supports a spindle 15, FIG. 5, to the end of which a rotatable magnetic driver 16 is fixed. A packing plate 17 is secured to the end of the rotatable magnetic driver 16 in co-axial relation with the spindle 15 to be rotated by an electric motor 18 mounted on the headstock 13. The packing plate 17 serves to fix the workpiece W on its ring-shaped end by magnetic attraction to render rotation to the workpiece W which is rotatably carried by a pair of shoes, for example, a front shoe 40 and a rear shoe 43 as shown in FIG. 2. Therefore, the workpiece W is ground at a working station wherein it is rotatably carried by the front and rear shoes 40 and 43 and is rotated by the electric motor 18.

A common plane 20 is vertically mounted on the side of body 12 at a predetermined position relative to the body 12 in the same plane of the ring-shaped end of packing plate 17. A loading chute 21 is inclined downwardly in the direction of the grinding wheel and is fixed on the upper portion of the common plane 20 to guide and store workpieces yet unoperated on being supplied from the left end thereof in association with an angle plate 22 and a vertical plate 23. A stop plate 24 is secured to the lower end of the loading chute 21 in parallel relation with the inclination of the loading chute 21. On the opposite side of the vertical portion of loading chute 21, a roller 25 is carried at the lower end ofa rod 27 mounted at its upper end on the vertical plate 23 so as to be rotatable in the clockwise direction until the angular position thereof is parallel to the vertical portion of the loading chute 21. A spring 26 is connected to the lower portion of the loading chute 21 and to the rod 27 for uring the roll 25 toward the vertical portion of the loading chute 21 or the foremost workpiece of the stored unground workpieces being in the loading chute 21. Thus, the foremost workpiece is suppored at a ready station from which the workpiece may be taken out to be transferred to a working station by a loading arm 30, on the end of which a plug 31 is formed to engage with the bore of the workpiece. The loading arm 30 is secured to the right end of a loading arm-shaft 32 rotatably and slidably mounted on the body 12 as shown in FIG. 3.

The front shoe 40 is mounted on the top of a holder 42 so as to be slightly rotatable thereby to fit the peripheral surface of the workpiece. The holder 42 is adjustably. mounted on an attaching plate 41 which is secured to the upper portion of work support 14 fixedly mounted on the base 11. The front shoe 40 is located to be in supporting engagement with the lower right portion of the workpiece W, as viewed in FIG. 2. On the other hand, the rear shoe 43 is pivotally mounted on the right end ofa holder 46 which is adjustably fixed to an attaching plate 45. The attaching plate 45 is securedly mounted on a swivel base 44 which is secured to a flange of a shaft 47, shown in FIG. 5, rotatably mounted on the body 12 in parallel with the loading arm-shaft 32. Referring particularly to FIGS. 4 and 5, a connecting rod 48 is pivotally connected to the swivel base 44 by a pin 49 at one end thereof, and at the other end thereof is pivotally connected to the right end of a rotating plate 51 by a pin 52. The rotating plate 51 is secured to a flange of a shoe-rotating shaft 50 rotatably mounted in the body 12 in parallel with the shaft 47. A connecting piece 53 is pivotally mounted on the pin 52 to be connected to one end of a spring 55. The other end of the spring 55 is connected to the upper end of a bracket 54 mounted on the top of body 12. The spring 55 serves to resiliently draw the connecting piece 53 upwardly so that the swivel base 44 is urged toward its right limit formed by the abutting engagement of a stop 57 fixed thereto with a stop 56 projecting out of the body 12. The rear shoe 43 is forwardly moved in a nearly horizontal direction by the clockwise rotations of swivel base 44 owing to the tension of spring 55 and is rearwardly movable upon clockwise rotation of the shoe-rotating shaft 50 in opposition to this tension. The clockwise moment of rear shoe 43 is increased by the link mechanism comprising the aforementioned rotating plate 51, pins 49 and 52, connecting rod 48, and swivel base 44. Therefore, although the tension of spring 55 is not very great, the spring 55 can provide the rear shoe with such rigidity to sufficiently oppose a grinding resistance. Besides, the retracting movement of rear shoe 43 is accomplished by a relatively small moment rendered to the shoe-rotating shaft 50, being just enough to oppose the force of spring 55. As shown in FIG. 14, for example the front and rear shoes 40 and 43 are adjusted to be positioned so that the rotation center P1 of workpiece W supported at the working station is eccentric by A1 relative to the center P2 of spindle 15, whereby the eccentric moment FAl is rendered to the rotating workpiece between the front and rear shoes 40 and 43.

Below the loading chute 21, a discharge chute 60 is fixed on the common plate 20, with an inclination to the workingstation. The right end portion of the discharge chute 60, as shown in FIG. 2, extends into the space between the front and rear shoes 40 and 43 and is adjacent to the workpiece in the working station. Accordingly, a completed workpiece is removed from the working position into the discharge chute 60 because of the eccentric moment FAl rendered thereto when the rear shoe 43 is laterally retracted.

An unloading arm 61 is fixed to the right end of an unloading arm-shaft 62 which is rotatably and slidably mounted on the body 12 as is the loading arm-shaft 32. The unloading arm 61 serves to downwardly carry out the completed workpiece from the working station through an abutting engagement with the upper periphery of the ground workpiece and also performs a miscellaneous function in the unloading operation by preventing the ground, or completed,workpiece from flying out of the discharge chute 60, upon being dropped therein. The right end portion of the unloading arm 61 is normally located slightly apart from the upper periphery of the workpiece.

Driving means for the loading and unloading arms 30 I and 61 and rear shoe 43 are described hereunder in detail with reference especially to FIGS. 3, 4, 5, 6 and 7. The loading arm-shaft 32 is rotatably and axially slidably mounted on the body 12 through bearings 70 and '71 below the working station, while the unloading armshaft 62 is rotatably and axially slidably mounted on the body 12 through bearings 72 and 73 above the working station in parallel with the loading arm-shaft 32, as shown in FIG. 3. A driving shaft 74 is rotatably mounted on the body 12 through bearings 75 and 76 at a position being substantially equidistant from the loading and unloading arm shafts 32 and 62 and the shoerotating shaft 50,FIG. 5, and parallel therewith. On the right portion of the driving shaft 74 is securedly mounted a peripheral cam 77 serving to rotate the to rotate the shoe-rotating shaft 50 and the unloading arm-shaft 62, as best shown in FIG. 6. Concentrically secured the left portion of driving shaft 74 are cylindrical cams 79 and 80 for causing arm-shafts 62 and 32, respectively, to be axially displaced, as shown in FIG. 3. A swing follower 82 is mounted on a serrated portion of the loading arm-shaft 32 and is restrained against axial movement by sleeves 35 and 36 which are fixed to the body 12. The loading arm-shaft 32 thus is slidably engaged within the swinging follower 82 and is drivingly engaged rotationally with the swinging follower 82. The swinging follower 82 rotatably supports a follower roller 81 in abutting engagement with the peripheral cam 77, as shown in FIGS. 3 and 6. The swinging follower 82 is normally urged toward the peripheral cam 77 by a spring 83, as shown in FIG. 6, so that the follower roller 81 may be held in an abutting engagement with the peripheral cam 77. Therefore, the rotation of driving shaft 74 provides the follower 82 with its swinging movement thereby to rotate the loading armshaft 32.

Similarly, on the left end of the shoe rotating shaft 50, there is securedly mounted a swinging follower which rotatably supports a follower 84 held in an abutting engagement with the peripheral cam 78 by the spring 55, as shown in FIGS. 5 and 6. Therefore, the rotation of driving shaft 74 advances and retracts the rear shoe 43 relative to the workpiece through the shoe rotating shaft 50 and the swivel base 44, FIG. 4.

A connecting pin 86, FIGS. 6 and 9, is secured to and projects beyond the swinging follower 85 to engage an elongated slot 89 formed on the lower portion of a connecting rod 88 which is pivotally mounted on a connecting member 87 at the upper end thereof. The connecting member 87 is secured to the unloading armshaft 62 having a counterclockwise moment rendered by a spring 90. The unloading arm-shaft 62 is clockwisely rotated by the pushing movement of connecting pin 86 in abutting engagement with the upper end of the elongated slot 89 when the shoe-rotating shaft 50 is clockwisely rotated in accordance with the profile of peripheral cam 78. On the right end of unloading arm shaft 62 is fixedly mounted a stop member 91 having an arm 92 thereon, the left side surface 93 of which is adapted to be held in abutting engagement with the rightside surface 96 of the projection of a stop rod which is pivotally mounted on a bracket 94 fixed to the body 12. The stop rod 95 is outwardly urged by a spring 97, FIG. 3, so as to engage with a roller 98 rotatably mounted on the end of arm 92 when the unloading arm-shaft 62 is clockwisely rotated, thus holding the unloading arm-shaft 62 at the lower swing end of arm 92, wherein the leftside surface 93 of arm 92 is in holding engagement with the rightside surface 96 of stop rod 95, against the force of spring 90 in spite of the release of the clockwise moment by the connecting pin 86 with respect to the unloading arm-shaft 62.

In FIG. 3, numeral 99 designates an adjusting plate which serves to adequately adjust the backlash in the spline engagement between the swinging follower 82 and the loading arm-shaft 32. Similarly, an adjusting plate 100 serves to adjust the backlash in the spline engagement between the connecting member 87 and the unloading arm-shaft 62 through a relative rotating torque rendered therebetween.

Follower rollers 111 and 112 are rotatably mounted on opposite ends of a supporting rod 110 in abutting engagement with the projecting ends of cylindrical earns 79 and 80, respectively, as shown in FIGS. 3 and 13. The supporting rod 110 is mounted on the loading and unloading arms 32 and 62 through anti-friction thrust bearings 115 and 116 in abutting engagement with the cylindrical earns 79 and 80. The opposite ends of supporting rod 110 are engaged with the left ends of arm-shaft 62 and 32, which are leftwardly urged by compressive springs 113 and 114 disposed respectively between flange portions on arm-shafts 62 and 32 and the body 12, through the anti-friction thrust bearings 115 and 116, respectively. The cylindrical cams 79 and 80 each have the same cam profile and are secured to the driving shaft 74 in a phase difference according to the angular positions of follower rollers 111 and 112 so that the arm-shafts 62 and 32 may be periodically axially moved at the same velocity. Since the aforementioned retaining engagement between the arm 92 and the stop rod 95 is released when the unloading armshaft 62 is rightwardly moved, the arm-shaft 62 is then counterclockwisely rotated by the force of spring 90.

The driving mechanism for driving shaft 74 is described herebelow with reference especially to FIGS. 3 and 7.

A driven gear 120 is rotatably mounted on the left end of driving shaft 74 and is connected with a clutch member 121 keyed to a tapered portion of driving shaft 74 through a one-way clutch 122. A wedge-shaped notch 123 is formed on the periphery of clutch member 121. A cylinder 126 serving to position the initial angular position of the driving shaft 74 is securely mounted on the rear of body 12 so that an engaging portion 125 formed on the end ofa piston rod 124 may engage with the wedge-shaped notch 123 formed on the periphery of clutch member 121. A piston 103 is slidably received in the cylinder 126 and is urged toward the clutch member 121 by a spring 102 received in a right chamber 128, as viewed in FIG. 7. The driven gear 120 is meshed with a large gear 131 of driving gears 130 to be rotated thereby. The driving gears 130 are rotatably mounted on a bracket 132 secured to the rear of body 12, as shown in FIG. 3. On the bracket 132 is securely mounted a fluid cylinder 133 which slidably receives a piston 101 and a piston rod 134, on which rack teeth 104 are formed to meshingly engage with a small gear 138 of driving gears 130. The stroke of piston 101 is designed so as to rotate the driving shaft 74 a little more than 360.

The operation of the preferred embodiment having the aforementioned construction will be described herebelow with reference to a following CYCLE DIA- GRAM and the fluid circuit of FIG. 8.

The CYCLE DIAGRAM shows the retraction and advancement of rear shoe 43, the swinging rise and fall of loading and unloading arms 30 and 61, and the left and right movement of arms 30 and 61 in accordance with the rotation angle of driving shaft 74. In the CYCLE DIAGRAM, when the driving shaft 74 is in the angular position of or in an initial position, the rear shoe 43 is in the end of advancement, the unloading arm 61 in the end of swing rise, and the loading arm 30 in the end of swing rise. Then, the piston 101 is in the retracted position wherein a limit switch 151 is operated, while the piston 103 of cylinder 126 is in the advanced end wherein a limit switch 153 is operated.

ROTATION ANGLE OF DRIVING SIIAFI In the aforementioned situation, when a magnetic change-over valve 140 is changed to position I, fluid under pressure from a source, not shown, is provided from the port B1 to the left chamber 127 of cylinder 126 through a check valve 146, so that the piston rod 124 is retracted to release the engagement between the wedge-shaped notch 123 and the engaging portion of piston rod 124. Then, since the left chamber 127 and a port 129 are interconnected upon the retraction of the piston, the fluid under pressure is applied to a pilot chamber 148 to change a hydraulic change-over valve 143 to its position II, whereby the fluid under pressure from the port B1 is supplied to the right or rear chamber 136 of cylinder 133 through ports P2 and A2 of the hydraulic change-over valve 143. Since the fluid under pressure in the left or front chamber is returned to a reservoir R through a variable throttle 141 and ports A1 and T1, the piston rod 134 is leftwardly advanced at the feed rate defined by the variable throttle 141. The driving shaft 74 is counterclockwisely rotated by the advancement of piston rod 134, whereupon the follower roller 84 follows the rising or working profile portion of the peripheral cam 78 to thereby be clockwisely rotated about the axis of shoe-rotating shaft 50, as best shown in FIG. 9, which is clockwisely rotated against the tension of springs 55,FIG.4, and 90,as best shown in FIG. 9. The swivel base 44 is counterclockwisely rotated about the axis of shaft 47, so that the rear shoe 43 is laterally retracted away from the working station, as shown by the phantom line in FIG. 10. Simultaneously, the unloading arm shaft 62 is clockwisely rotated by the clockwise rotation of connecting pin 86 against the tension of spring 90, so that the unloading arm 61 is downwardly swung from the position shown by real line to that shown by phantom line in FIG. 10, thus surely or positively unloading the operated workpiece into the discharge chute 60.

While the operated-on workpiece is being unloaded, the right chamber 128 of cylinder 126 is connected with a port 137 formed on the cylinder 137 to provide a part of fluid under pressure supplied via the port A2 with the right chamber 128 through the port [37, whereby the piston 103 of cylinder 126 is leftwardly moved by the force of spring 102 and the pressure of fluid until the abutting portion 125 is brought into an abutting engagement with the periphery of clutch member 121. While the completed workpiece W is being moved into the discharge chute 60, that is, when the driving shaft 74 is rotated to the a angular position in the CYCLE DIAGRAM, the follower roller 81 follows the rising or working profile portion of peripheral cam 77 thereby to be clockwisely rotated about the axis of loading arm-shaft 32 against the force of spring 83, as shown in FIG. 11, so that the loading arm 30 is clockwisely or downwardly swung to transfer the unoperated workpiece W1 held by the plug 31 thereof from the loading to the working station, as shown in FIG. 12. At the a2 angular position of rotation of shaft 74, the follower roller 84, FIG. 9, is in abutting engagement with the apex portion of peripheral cam 78 and has been rotated against the force of springs 55 and 90 to a position wherein the connecting rod 88 and the connecting member 87 and the like are fragmentally shown by phantom lines in FIG. 9. Then, the rear shoe 43 has been retracted to the position shown by the phantom line in FIG. 10, and the unloading arm 61 associated with the rear shoe 43 has been also swung to the lower limit of the motion thereof shown by a phantom line in FIG. 10. When the unloading arm 61 reaches its lower limit, the arm 92, FIG. 4, is brought into abutting engagement with the stop rod 95. After the rear shoe 43 reaches the retracting or left limit of its motion, the follower roller 84 follows and is urged toward the falling profile portion continuing from the rising profile portion of peripheral cam 78 by means of spring 55 to be counterclockwisely rotated about the axis of shaft 50, so that the swivel base 44 is clockwisely or forwardly rotated about the axis of shaft 47, FIG. 4, to move the rear shoe 43 toward the grinding wheel S. On the other hand, the unloading arm 61 is retained at its lower limit by the retaining engagement provided between the arm 92 and the stop rod 95. The loading arm, which is loading the unground workpiece, reaches the lower limit of its swing motion, or the working station, wherein it holds the workpiece, since the follower roller 81 follows the base profile portion of peripheral cam 77, when the driving shaft 74 is rotated to the a6 angular position. Thereafter, the follower roller 84 follows the moderately falling profile portion to counterclockwisely rotate the swinging follower and thereby feed the rear shoe 43 forward. Since the stop 57 is brought into holding engagement with the stop 56 when the driving shaft 74 is rotated to the a3 angular position, the rear shoe 43 abuts to support the unoperated workpiece W being held at the working station by the loading arm 30 and the front shoe 40, as shown by the frag-' mentary real line in FIG. 10. A pushing force caused by the spring 55 is placed against the swivel base 44 being magnified through the agency of the link mechanism, so that a high rigidity capable of bearing the grinding resistance is rendered to the rear shoe 43 and a gap caused in the movable portion of the aforementioned shoe-driving means is eliminated thereby to prevent vibration. Since the feed rate of the rear shoe 43 is gradually decreased by the operation of the link means as the rear shoe 43 approaches the workpiece, the rear shoe 43 is moderately brought into engagement with the workpiece so as not to push the workpiece toward the grinding wheel. Though the driving shaft 74 continues to rotate, the counterclockwise rotation of follower roller 84 is stopped by the stop 56 to thereby maintain a constant predetermined space between the base portion of the peripheral cam 78 and the follower roller 84 till the roller 84 engages with the working profile portion of the cam 78 corresponding to the retraction step of the rear shoe 43.

When the driving shaft 74 is rotated to the a9 angular position, follower rollers 111 and 112 follow the rising terminal profile portions of cylindrical earns 79 and 80, respectively, to rightwardly move arm-shafts 32 and 62 at the same time from the position shown by the real line in FIG. 13. Furthermore, since the follower rollers 111 and 112 engage the base profile portions of cylin drical cams 79 and 80 corresponding to the right limit of the arm-shaft motion when the driving shaft 74 is rotated to the a4 angular position of the CYCLE DIA- GRAM, the arm-shafts 32 and 62 reach the position spaced from the left limit thereof by a distance 1, as shown by phantom line, whereby the engagement of plug 31 with the unground workpiece is released, and also the unloading arm 61 is axially displaced to a position to prevent striking of the shoes 40 and 43 in its upward movement. When the unloading arm 61 reached the limit of its rightward motion, the engagement of arm 92 with the stop rod is released, whereby the unloading and loading arms 61 and 30 are counterclockwisely rotated by the force of spring 90 at a rapid rate until the'upper end of the elongated slot 89 abuts the pin 86. On the other hand, since the follower roller 81 is brought into engagement with the working surface corresponding to the angular division line of the angle of rise when the driving shaft 74 is rotated to the a7 angular position, the swinging follower 82 and the loading arm-shaft 32 are counterclockwisely rotated by the force of spring 83 to swing the loading arm 30 upwardly from the working station shown by phantom line in FIG. 12 to the loading or ready station shown by real line. The loading arm 30 is maintained at the loading station, since the follower roller 81 is kept by the force of spring 83 in contact with the inner terminal surface of peripheral cam 77 corresponding to the upper limit of loading arm motion when the driving shaft 74 is further rotated to the a8 angular position.

Since the follower rollers 111 and 112 are brought into contact with the left terminal surfaces of cylindrical cams 79 and 80 corresponding to the left limit of the axial motions of arm-shafts 32 and 62 when the driving shaft 74 is rotated to the a 10 angular position, the arm-shafts 32 and 62 which have previously been shifted to the right limit of axial motion thereof are now shifted by the force of springs 113 and 114 to the left limit of their axial mobility. Thereby, the plug 31 of loading arm 30 is brought into holding engagement with the next succeeding unoperated-on workpiece supported at the loading station, while the unloading arm 61 is shifted so that the end portion thereof is positioned just above the workpiece supported at the working station. Thereafter, the arms 30 and 61 are maintained at the left limit, shown by real line in FIG. 13, of the axial motions thereof during the time that the driving shaft 74 is further rotated to the a 11 angular position.

When the full revolution of driving shaft 74 is accomplished, the abutting portion of piston rod 124 is re-engaged with the wedge-shaped notch 123 of clutch member 121 to thereby keep the driving shaft 74 in its initial position of rotation, as shown in FIG. 8. The piston rod 134 then operates the limit switch 152 to change the magnetic change-over valve to its position 11, whereby fluid under pressure supplied from the port A 1 of magnetic change-over valve 140 is applied to the left chamber 135 of fluid cylinder 133 and to the pilot chamber 144 of hydraulic change-over valve 143 through a check valve 142. Accordingly, the hydraulic change-over valve 143 is changed to its position I, so that the fluid discharged from the right chamber 136 of fluid cylinder 133 is returned to the reservoir R through check valves 150 and 149, a variable throttle valve 147, and the ports B1 and T1 of magnetic change-over valve 140. Thus, the piston rod 134 is moved to the right or rear end at a rapid feed rate set by the variable throttle valve 147 without rotating the driving shaft 74 positioned at its initial position, since the one way clutch 122 is posed between the clutch member 121 keyed to the driving shaft 74 and the driven gear 120 rotatably mounted on the driving shaft 74 in meshing engagement with the driving gear 130.

Thus, after the devices and movable parts described herein have been returned to their initial positions, as shown in the drawings, and the loading and unloading operations of the respective workpiece are completed, the grinding wheel S is moved by the feed device 3 toward the workpiece to grind it. After the grinding operation is accomplished and the grinding wheel is again retracted, the loading and unloading operations as mentioned above are repeated.

The accomplishment of the grinding operation is controlled by a sizing device 160 mounted on the work support 14, as shown in FIGS. 15 and 16. The sizing device 160 comprises a sizing head 162 which pivotally supports a measuring feeler 161 in contacting relation with the peripheral surface of the workpiece W. A displacement detector 163 is mounted in the sizing head 162 in operative engagement with the end of measuring feeler 161 to detect displacement of measuring feeler 161. The sizing head 162 is adjustably mounted on an inclined guideway 165a formed on the top ofa pedestal 165 which is mounted on the base 11. The inclined angle of the guideway 165a is equal to the angle of the line connecting the center of the workpiece supported by the pair of shoes 40 and 43 and the center axis of loading arm-shaft 32, as shown in FIG. 15. Besides, a contacting anvil 161a fixed to the end of measuring feeler 161 lies in a plane passing through the rotation axes of the workpiece and the loading arm 30, and the measuring feeler 161 is rotatably supported by a cross spring 166 so as to be displaced along the plane. Accordingly, the working diameter of the workpiece W is measured by the displacement of the measuring feeler 161 which is in contact with a point which is at a position on the peripheral surface of the workpiece opposite to the two points of contact of shoes 40 and 43. The displacement amount of measuring feeler 161 in the measurement by three points of contact is larger than that in the measurement by two points of contact, that is, the displacement of measuring feeler 161 is generally enlarged and is larger than the change of the working diameter to thereby increase the measuring sensitivity of sizing device 160 and to enable the sizing device 160 to perform a highly accurate measurement. Furthermore, the measuring feeler 161 is extended toward the workpiece in substantially parallel relation with the rotation axis of the workpiece, and the point of contact of measuring feeler 161 with the workpiece is on the loading locus of the workpiece W. Therefore, the sizing device 160 may be fixedly mounted on the pedestal 165, since interference thereof with the workpiece is averted in the loading operation associated with the retracting movement of rear shoe 43.

The adjustment or displacement of the sizing head 162 along the inclined guideway 165a is performed when the workpiece being loaded is one having a different diameter. The sizing head 162 is moved by a piniondriving shaft which is meshingly engaged with a rack 169 formed on the center portion of the inclined guideway 165a after the release of clamping bolts 167 and 168 so that the sizing point of the changed workpiece is masterset as is well known to those skilled in the art.

The displacement detector 163 generally is a differential transformer which comprises a core, not shown, movable in response to the displacement of measureing feeler 161, and energized windings for generating an output signal corresponding to the displacement of the core therewithin. The output signal may be applied to a conventional schmidt circuit, which provides a sizing signal when the output signal is above a preset voltage level corresponding to a desired diameter of changed workpieces.

The entire operation cycle according to the present invention is described herein below in brief.

The wheel head 2 is moved away from the ground workpiece by the cutting head amount when a sizing signal is transmitted from the sizing device 160. Simultaneously, the rear shoe 43 is retracted from the working station, and the magnetic driver 16 is deenergized. Thus, the completed workpiece just operated on is unloaded into the discharge chute 60 in response to the retracting movement of rear shoe 43. A little after this movement, the loading arm 30 starts the loading operation thereof and in turn the rear shoe 43 starts to move back into the working station or toward the front shoe. When the unoperated or new workpiece is loaded at the working station, the rear shoe 43 is disposed and strongly fixed at the forward limit of movement thereof being restrained by the stop 56 through the spring 55 and the link mechanism. After the completion of the loading operation, the magnetic driver 16 is reenergized to come into driving engagement with the new workpiece mounted on the shoes 40 and 43. The grinding operation is commenced by the cutting feed of the wheel head 2 and the rotation of the magnetic driver 16. Then, the loading and unloading arms 30 and 61 are returned to their upper limits or normal positions. The wheel head 2 is forwardly moved for grinding the workpiece without the conventional rapid feed movement of a spare escapement-stroke. When the workpiece is ground to a predetermined size, the sizing device 160 transmits a sizing signal to retract the wheel head 2. The magnetic driver 16 is then deenergized, and the rear shoe 43 is moved away from the workpiece just operated on, thus dicharging the workpiece into the discharge chute 60 through the operation of the unloading arm 61.

Although certain specific embodiments of the invention have been shown and described, it is obvious that many modifications and variations thereof are possible in light of the above teachings. It is to be understood therefore, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

1 claim:

1. A grinding machine of the type having a bed, a grinding wheel, and a headstock, comprising; 

1. A grinding machine of the type having a bed, a grinding wheel, and a headstock, comprising; a pair of shoes mounted on said bed for positioning a workpiece in a working station defined thereby during a grinding operation, one of said shoes being fixedly mounted adjacent to said grinding wheel, and the other of said shoes being movably mounted opposite said grinding wheel relative to the one of said shoes; a loading chute for holding unground workpieces, said loading chute having a ready station at one end thereof; a discharge chute mounted below said shoes, one end of said discharge chute being disposed below and between said shoes; stop means fixedly mounted for defining the end of movement of the other of said shoes; means for moving the other of said shoes toward and away from said stop means to position a workpiece in said working station and so as to discharge a ground workpiece downwardly between said shoes to the one end of said discharge chute, respectively; driving means mounted on said headstock for rotating said workpiece being in holding engagement with said workpiece; and transfer means for transfering said workpiece from said ready station downwardly into said working station in cooperation with said movement of the other of said shoes.
 2. A grinding machine according to claim 1, in which said moving means moves the other of said shoes in a substantially horizontal direction toward said grinding wheel.
 3. A grinding machine according to claim 2, which further comprises: a body mounted on said bed; and a swivel base movably mounted on said body for adjustably mounting the other of said shoes, said swivel base being moved by said moving means toward and away from said stop means.
 4. A grinding machine according to claim 3, in which said moving means comprises: linking means connected to said swivel base at one end thereof for rotating said swivel base toward and away from said stop means; means connected to said linking means for urging said swivel base toward said stop means; and actuating means mounted on said body for causing said linking means to move said swivel base away from said stop means against the force of said urging means.
 5. A grinding machine according to claim 1, in which said transfer means comprises; a body mounted on said bed; a loading arm rotatably mounted on said body; first means mounted on said body for swinging said loading arm between said ready and said working stations; and second means mounted on said body for axially shifting said loading arm to engage and disengage said unground workpiece at said ready and said working stations, respectively.
 6. A grinding machine according to claim 5, in which said first means comprises: an actuator; a driving shaft rotatably mounted on said body, being driven by said actuator; a first peripheral cam connected to said driving shaft; a first shaft movably mounted on said body; said loading arm being secured to said first movable shaft; a swinging follower mounted on said first movable shaft; and means for urging said swinging follower toward said first peripheral cam.
 7. A grinding machine according to claim 5, in which said second means comprises: an actuator mounted on said body; a driving shaft rotatably mounted on said body, being driven by said actuator; a first cylindrical cam concentrically mounted on said driving shaft; a first shaft movably mounted on said body, said loading arm being secured to said first shaft; a follower mounted on said first shaft for axially moving said first shaft in accordance with the contour of said first cylindrical cam; and means for urging said follower toward said first cylindrical cam.
 8. A grinding machine according to claim 5, which further comprises: an unloading arm movably mounted on said body; third means mounted on said body for swinging said unloading arm to push down a ground workpiece into said discharge chute; and fourth means mounted on said body to axially shift said unloading arm into and out of said working station.
 9. A grinding machine according to claim 8, in which said fourth means comprises: an actuator mounted on said body; a driving shaft rotatably mounted on said body, being driven by said actuator; a second shaft rotatably and slidably mounted on said body; said unloading arm being secured to said second shaft; a second cylindrical cam concentrically mounted on said driving shaft; a follower mounted on said second shaft for axially moving said second shaft in accordance with the contour of said second cylindrical cam; and means for urging said follower toward said second cylindrical cam.
 10. A grinding machine according to claim 8, further comprising: a swivel base movably mounted on said body for adjustably mounting the other of said shoes; linking means connected to said swivel base at one end thereof for moving said swivel base substantially radially of said grinding wheel; means connected to said linking means for causing said linking means to urge said swivel base toward said grinding wheel; and actuating means mounted on said body for causing said linking means to move said swivel base away from said grinding wheel against the force of said urge causing means.
 11. A grinding machine according to claim 10, in which said actuating means comprises: an actuator mounted on said body; a driving shaft rotatably mounted on said body, being driven by said actuator; a peripheral cam connected to said driving shaft; a shaft rotatably mounted on said body in driving engagement with the other end of said linking means; and a swinging follower connected to said shaft in contacting engagement with said peripheral cam for rotating said shaft.
 12. A grinding machine according to claim 11, in which said third means comprises: a second shaft rotatably mounted on said body, being driven by said actuator; a member fixed to said second shaft; a connecting rod eccentrically mounted on said second shaft through said member at one end thereof and drivingly connected to the swinging follower of said swivel base movaBle means at the other end thereof; and means for returning said unloading arm to the upper limit thereof when said unloading arm is axially moved away from the one of said shoes.
 13. A grinding machine according to claim 1, further comprising: a pedestal fixedly mounted on said bed; and a sizing device for measuring the diameter of said workpiece, including a sizing head adjustably mounted on said pedestal, a measuring feeler mounted on said sizing head in parallel with the rotational axis of said workpiece on said shoes so as to contact said workpiece at a position thereon opposite the engaging points of said shoes, and means mounted on said sizing head for detecting the displacement of the said measuring feeler.
 14. A grinding machine according to claim 5, which further comprises: a pedestal fixedly mounted on said bed; and a sizing device for measuring the diameter of said workpiece, including a sizing head adjustably mounted on said pedestal, a measuring feeler mounted on said sizing head in parallel with the rotational axis of said workpiece at a position on said workpiece opposite the contacting points of said shoes, and means mounted on said sizing head for detecting the displacement of said measuring feeler.
 15. A grinding machine according to claim 14, in which the engaging portion of said measuring feeler with said workpiece is in the plane passing through the rotational axes of said loading arm and said workpiece.
 16. A grinding machine according to claim 15, in which said sizing head is movable within said plane when the position of said sizing head is adjusted. 